Pulp is the raw material used to manufacture paper and paper products. It is produced by the mechanical and/or chemical treatment of plant substances that contain cellulose. Such treatments generally eliminate at least a portion of the non-cellulose constituents of such plant substances, break up the plant substances into fiber bundles or smaller fiber entities, and generally to some extent hydrate the plant substance. These treatments are generally known as pulping processes, i.e., processes for producing pulp.
Chemical treatments of plant substances to produce pulp generally act by eliminating constituents such as lignin that hold plant substance fibers together, disintegrating the substance into its component fibers. Mechanical treatments rely mainly on friction to separate fibers or fiber bundles.
Pulping can be achieved through essentially all chemical treatment (chemical pulping), through essentially all mechanical treatment (mechanical pulping), or through a combination of chemical and mechanical treatments (semichemical pulping). Thus mechanical treatments are used in both mechanical pulping and semichemical pulping.
In mechanical treatments, energy consumption is one of the most important production factors, and can well be the most important problem. Reduction in energy consumption, without a concomitant reduction in pulp quality, is greatly desired in the pulping field.
Pulp quality is generally measured by pulp strength (bursting strength of the paper products manufactured therefrom) and pulp freeness (readiness with which water drains freely from pulp material). The higher the pulp strength and the lower the pulp freeness, the higher the pulp quality.
Pulp strength of pulp produced at least partially by mechanical treatment is believed directly related to, and directly proportional to, the energy consumed in such mechanical treatment. Pulp freeness is also believed directly related to, and inversely proportional to, the energy consumed in the mechanical treatment.
Reducing energy consumption in mechanical treatment of pulp material without reducing the resultant pulp strength of reducing the decrease in pulp freeness associated with the pulping process, while maintaining the same level of production of pulp, is highly desirable. The level of energy consumption per unit time could be kept as high as normal, increasing the mill throughput, i.e., the pulp produced per unit time, and thus reducing the energy consumed per unit pulp production. In multiple mechanical refiner operations, the number of refiners utilized for a given day's production could be reduced, or the refiners could be operated for shorter periods of time each day. The end result in any case would be a savings in energy cost and a conservation of energy resources.
Such a reduction of energy consumption by the use of an additive whose use cost is small in proportion to the cost of the energy saved is also extremely desirable for pulp mills.